Effect of Zener-Hollomon parameter on hot deformation behavior of CoCrFeMnNiC0.5 high entropy alloy
Effect of Zener-Hollomon parameter on hot deformation behavior of CoCrFeMnNiC0.5 high entropy alloy
复制标题
Zener-Hollomon参数对CoCrFeMnNiC0.5高熵合金热变形行为的影响
DOI：
10.1016/j.msea.2019.138483
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发表时间：
2019
期刊：
影响因子：
6.4
通讯作者：
Liu Yong
中科院分区：
文献类型：
--
作者：
Wang Yitao;Li Jianbo;Xin Yunchang;Li Changzheng;Cheng Yao;Chen Xianhua;Rashad Muhammad;Liu Bin;Liu Yong
研究了含碳面心立方CoCrFeMnNi高熵合金（HEA）在700 °C ~ 1000 ° C温度范围和0.001 ~ 1 s−1应变速率范围内的热压缩变形机制。CoCrFeMnNiC0.5（at.%）合金的本构方程得到了能准确预测流变应力的合金。表观激活能Q = 362 kJ/mol，表明碳的加入导致了热变形过程中的加工硬化。讨论了不同Zener-Hollomon参数值下的变形机制。CoCrFeMnNiC 0. 5合金在700 °C变形时的Zener-Hollomon参数（lnZ）随着应变量和应变速率的增加而增加。在低Zener-Hollomon条件下（lnZ≤40），位错壁（DDW）通过产生长程背应力而引起明显的加工硬化。随着lnZ的增加，固溶体中的碳的加入有效地减少了位错的交叉滑移，并导致从良好发展的DDW向微带（MB）的转变。MBs可以被视为另一种输入的变形模式，以提供额外的加工硬化源。在高Zener-Hollomon条件下（lnZ>46），微气泡的显著影响导致稳定流动后的流动应力略有增加。在ε = 0.8时变形的CoCrFeMnNiC0.5HEA的Zener-Hollomon参数随着温度的升高和应变速率的降低而减小。不连续动态再结晶（DDRX）是组织演化的主要机制，在低lnZ（lnZ≤40）条件下，DDRX导致流变软化。DDRX形核是由于M23 C6碳化物诱导位错运动的微带和钉扎效应导致晶界局部膨胀。
Hot compressive deformation mechanism of the carbon-contained face-centered cubic CoCrFeMnNi high-entropy alloy (HEA) was investigated in the temperature range between 700 °C and 1000 °C and in the strain rate range between 0.001 and 1 s−1. The constitutive equation of CoCrFeMnNiC0.5(at.%) alloy was obtained, which can predicate the flow stresses accurately. The apparent activation energy (Q) was calculated as 362 kJ/mol, suggesting that the carbon addition cause the work hardening during hot deformation. The deformation mechanisms at various Zener–Hollomon parameter values have been discussed. The Zener-Hollomon parameter (lnZ) of CoCrFeMnNiC0.5alloy deformed at 700 °C increases with the increasing of the strain and strain rate. At low Zener-Hollomon condition (lnZ≤40), density dislocation walls (DDWs) caused the obvious work hardening by producing a long-range back stress. With the lnZ increasing, the addition of carbon in solid solution effectively reduces the dislocation cross-slip, and causes the transition from well-development DDWs to microbands (MBs). MBs can be regarded as another imported deformation mode to provide additional work-hardening source. At high Zener-Hollomon condition (lnZ>46), the pronounced effect of MBs results in slight increasing of the flow stress after steady flow. The Zener-Hollomon parameter of CoCrFeMnNiC0.5HEA deformed at ε = 0.8 decreases with the temperature increasing and strain rate decreasing. Discontinuous dynamic recrystallization (DDRX) is the dominant microstructural evolution mechanism and leads the flow softening at low lnZ condition (lnZ≤40). The DDRX nucleation is attributed to the microbands and pinning effect on the dislocation movement induced by M23C6carbides, which can lead to local grain boundary expansion.